Yuan Haiwen

Research on harmonic current distribution of beijing's rail traffic power supply system

This paper will discuss the monitoring and data analysis of nonlinear load power quality by analyzing electrical railway, which is a typical nonlinear load in Beijing. Firstly, this paper will introduce a method of designing the software and hardware of a kind of highly accurate and large-capacity energy quality data recorder, which is capable of accurately recording voltage, electric current wave, etc., data on site for a long standing and can restore the original data with upper computer in lab. Secondly, this paper will analyze the data collected by the energy quality data recorder from Beijing Xiazhuang transformer substation, which is responsible for supplying electricity to Daqin railway and is a typical nonlinear electrical railway load. On the one hand this paper presents the complete data of fundamental current and harmonic current in a typical working day (as shown in graphs) and analyzes the correlation between fundamental current and main harmonic current. On the other hand, this paper also analyzes the amplitude of main harmonic current distribution with statistical methods and establishes an autoregressive (AR) model to illustrate the distribution of main harmonic current. From the above analysis we can get the key data for evaluating the impact generated by this transformer substation on the grids electrical energy quality.

Research on harmonic compensation effects for a kind of isolated power system

Due to the disadvantages of passive filter such as big size, easy occurrence of resonance with the power and the poor compensation effect, the active harmonic compensation technology was put forward in recent years. Compared with the harmonic compensation in the independent power system, active compensation supported by embedded technology can quickly achieve the single harmonic compensation and all compensation, with good compensation effect and flexible operation. An experimental platform to solve the harmonic current of the isolated oil rig power supply system is built up in this paper. Besides the introduction of the principles and compositions of active compensation device as well as the extraction and control of the compensation current, the results of harmonic compensation of the device in three-phase three-wire power system on the experimental platform is emphasized, as well as the methods to improve the compensation effect. The platform lays a solid foundation for the ultimate application of compensate device in the oil drilling power system.

Design of Distributed Synchronous Data Acquisition System for HVDC Corona Current

In order to collect the corona current in multiple locations of HVDC transmission lines, a distributed synchronous data acquisition system is designed and implemented. The system comprises a time server and a plurality of subsystems, the time server and the client computers in subsystems form a local area network through a switch. The distributed synchronous data acquisition system is designed based on NTP(Network Time Protocol), the Client/Server work mode is used in the system. At regular intervals, the time synchronization between clients and server is executed, the server sends collection command to each subsystem. The synchronization scheme of the corona current measurement system is realized by the software programming of the server and the client, and the synchronization precision can reach 1.725ms, which provides a solution for the large-scale distributed synchronous data acquisition.

Fiber-Based Remote Control Device and Engineering Application

In ultra-high voltage (UHV) corona current measurement system, remote control is needed between low voltage side and high voltage side. Many factors such as extreme temperature, sleet, strong electromagnetic interference and high voltage will affect the remote control device. According to the problem, the fiber-based remote control device is designed for the UHV corona current measurement system to control the power supply of high voltage side. To transfer signal in the circuit, fiber optic transceiver can make conversion between electric signal and optical one. The fiber-based remote control device provides a method for remote control in high voltage and strong electromagnetic environment. It has high speed and small attenuation.

Research on Data Consistency in Electric Field Measurement

Experimental studies are reported that measuring results of electric field mill are inconsistency, which affects their measuring accuracy. This paper introduces the principle of electric field measurement. Statistical analysis of calibration experimental results shows that measurement data obey normal distribution rule. Correlation analysis result indicates that the distance between two electrodes of field mill has a strong linear correlation with measure results. Linear model is established with the method of regression analysis. Finally, residual test verify the rationality of regression model.

Design of Distributed Current Source System Based on CAN Bus

A current source system based on CAN bus was designed. The system is used for distributed control of the current source. The current source module of the system is controlled by the AT89C52 micro controller, and the output current is bidirectional and adjustable. The current source module has high linearity and stability. The system operates simply, and it has high reliability. The system provides a practical solution for situations where bidirectional current source is required.

Research and Application of ATML for Aircraft Electric Power Diagnosis and Prognostic System

The technology of integrated health management (IHVM) is an important approach to improve the security, reliability and maintainability of airplanes and spacecrafts, and to reduce their cost significantly. Taken aircraft electric power system into consideration, it is one of the important equipment that provides electric energy for all electro-equipments in airplane. Its working state is a crucial to ensure airplane normal and secure flight, so the research of condition detection, fault diagnosis and prognosis is a great concern in the field of IHVM system. Aiming at interoperability and complexity of data exchanging for aircraft electric power diagnosis and prognostic system, a method of using ATML (automatic test markup language) based on XML (extensible markup language) is proposed in order to describe the information of devices and conditions for fault diagnosis and prognostic in the system. First, based on reference frame of integrated health management system, a distributed multi-level fault diagnosis and prognosis system structure that exchange data through ATML is designed. Secondly, condition monitor is a foundation of fault diagnosis and prognosis, and a schema of test information for aircraft electric power parameters is designed by using ATML after data of crucial fault is analyzed. The result shows that the method can implement seamless interaction among test, diagnosis and prognosis. At same time, sharing and transplant of test information and diagnostic knowledge is improved and the process of fault diagnosis is accelerated.